Inkjet printer ink

ABSTRACT

A water-based inkjet printer ink contains at least a colorant and a resin. The resin is a block copolymer, which contains at least one hydrophilic block and at least one hydrophobic block. Each of the blocks is a vinyl ether polymer. The ink further contains aluminum or an aluminum compound.

TECHNICAL FIELD

This invention relates to water-based inks suitably usable in inkjetprinters.

BACKGROUND ART

Inkjet recording has long been known as an image-forming process. Ininkjet recording, there are outstanding demands for images of higherquality, faster printing speed and high-speed fixing performance, andfrom an ecological standpoint, there is an ever increasing demand forenergy saving. Among these, the demand for a speed-up in the fixingprocess upon formation of an image and that for images of higher qualityare surging. With a view to achieving these improvements, investigationshave been made to develop a low-energy-consumption and high-speed fixingprocess in inkjet recording, resulting in proposals such as use of areactive ink with a reactive colorant contained therein (see JP 8-253717A) and use of a compound having reversible thermal gelation property(see JP 649399). However, there is still a larger room for improvementsin high-speed fixing performance.

With a view to meeting the above-described demands, the presentinvention has as an object thereof the provision of a water-based inkjetprinter ink (hereinafter simply called “ink” or “water-based ink”) whichhas excellent fixing property and permits stable ejection from nozzlesand formation of images with good abrasion resistance, waterproofnessand good marker resistance.

DISCLOSURE OF THE INVENTION

The above-described object can be achieved by the present invention tobe described hereinafter. Specifically, the present invention provides awater-based inkjet printer ink comprising at least a colorant and aresin, characterized in that the resin is a block copolymer comprisingat least one hydrophilic block and at least one hydrophobic block, eachof the blocks is a vinyl ether polymer, and the ink further comprisesaluminum or an aluminum compound.

In the ink, the molar ratio of the resin (A) to the aluminum or aluminumcompound (B), A:B, may be preferably from 1:5 to 10,000:3, morepreferably from 100:6 to 1,000:3.

The present invention also provides an ink jet recording processcharacterized in that images are, formed by an inkjet recording systemwhile using the ink according to the present invention.

BEST MODES FOR CARRYING OUT THE INVENTION

Based on certain preferred embodiments, the present invention will nextbe described in further detail. Components essential to the ink of thepresent invention are the colorant, resin and aluminum (or aluminumcompound) and an aqueous medium to be described subsequently herein.Among these, the resin and aluminum (or aluminum compound) act to havethe colorant, which is contained in the ink, fixed on a recording mediumsuch as paper after the ink is applied to the recording medium.

In the present invention, the resin for use in the ink is required to bea block copolymer comprising at least one hydrophilic block and at leastone hydrophobic block, in that each of the blocks is a vinyl etherpolymer. Those containing one or more hydrophobic blocks and two or morehydrophobic blocks or those containing two or more hydrophobic blocksand one or more hydrophilic blocks can also be used. These two or morehydrophilic blocks and/or these two or more hydrophobic blocks may be ofthe same type or of different types. As the block copolymer, a singleblock copolymer or a blend of two or more block copolymers can be used.Namely, in the copolymer block copolymers of the invention, an examplecan be an A-B diblock copolymer, an A-B-A tricopolymer, an A-B-Ctricopolymer, a C-B-A tricopolymer or a C-A-B tricopolymer, wherein A, Band C represent a hydrophilic block or a hydrophobic block,respectively, and each is not the same as the others. The structure ofeach copolymer can be linear, graft or the like, although a linear blockcopolymer is preferred.

As the resin, one obtained by polymerizing vinyl ethers as monomers andcontaining a polyvinyl ether structure is preferred because it forms astable dispersion with colorant particles. Particularly preferred is aresin at least one hydrophilic block of which is either an anionicpolyvinyl ether block or a diblock copolymer composed of a nonionicpolyvinyl ether block and an anionic polyvinyl ether block, because thecolorant particles dispersed in the ink medium are provided with furtherimproved stability. When the at least one hydrophilic block of the resinis a diblock copolymer composed of a nonionic polyvinyl ether block andan anionic polyvinyl ether block, a block copolymer composed of apolyvinyl ether block having hydrophobicity, the nonionic polyvinylether block having hydrophilicity and the anionic polyvinyl ether blockhaving hydrophilicity in this order is more desired because the colorantparticles dispersed in the ink medium are provided with still furtherimproved stability.

As the polyvinyl ether block having hydrophobicity and forming theabove-described resin, a block having a recurring unit structurerepresented by the following formula (1) is preferred:—(CH₂—CH(OR¹))—  (1)

In the above-described formula (1), R¹ represents an aliphatichydrocarbon group such as an alkyl, alkenyl, cycloalkyl or cycloalkenylgroup; or an aromatic hydrocarbon group one or more of carbon atoms ofwhich may be substituted by nitrogen atoms, such as a phenyl, pyridyl,benzyl, toluyl, xylyl, alkylphenyl, phenylalkyl, biphenyl orphenylpyridyl group. One or more of the hydrogen atoms on the aromaticring may be substituted by hydrocarbon groups. The carbon number of R¹may preferably range from 1 to 18.

R¹ can also be a group represented by —(CH(R²)—CH(R³)—O)_(p)—R⁴ or—(CH₂)_(m)—(O)_(n)—R⁴. In this case, R² and R³ each independentlyrepresents a hydrogen atom or a methyl group, and R⁴ represents analiphatic hydrocarbon group such as an alkyl, alkenyl, cycloalkyl orcycloalkenyl group, an aromatic hydrocarbon group one or more of carbonatoms of which may be substituted by nitrogen atoms, such as a phenyl,pyridyl, benzyl, toluyl, xylyl, alkylphenyl, phenylalkyl, biphenyl orphenylpyridyl group, with one or more hydrogen atoms on the aromaticring being optionally substituted by hydrocarbon groups, —CO—CH═CH₂,—CO—C(CH₃)═CH₂, —CH₂—CH═CH₂, —CH₂—C(CH₃)═CH₂. In each of these groups,one or more hydrogen atoms may be substituted by halogen atoms such asfluorine, chlorine or bromine atoms to chemically feasible extent. Thecarbon number of R⁴ may preferably range from 1 to 18. Preferably, p canrange from 1 to 18, m can range from 1 to 36, and n can be 0 or 1.

In R¹ and R⁴, examples of the alkyl and alkenyl groups can includemethyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, t-butyl, pentyl,hexyl, heptyl, octyl, nonyl, decyl, dodecyl, tetradecyl, hexadecyl,octadecyl, oleyl and linoleyl, and examples of the cycloalkyl andcycloalkenyl groups can include cyclopropyl, cyclobutyl, cyclopentyl,cyclohexyl, cyclooctyl and cyclohexenyl.

As the polyvinyl ether block having hydrophilicity, on the other hand, ablock having a recurring unit structure represented by the followingformula (2) is preferred:—(CH₂—CH(OR⁵))—  (2)

In the above-described formula (2), R⁵ is a group represented by—(CH₂—CH₂—O)_(k)—R⁶, —(CH₂)_(m)—(O)_(n)—R⁶, —R⁷X, —(CH₂—CH₂—O)_(k)—R⁷—Xor —(CH₂)_(m)—(O)_(n)—X. In this case, R⁶ represents a hydrogen atom, alinear or branched C₁₋₄ alkyl group, —CO—CH═CH₂, —CO—C(CH₃)═CH₂,—CH₂—CH═CH₂, —CH₂—C(CH₃)═CH₂, and R⁷ represents an aliphatic hydrocarbongroup such as an alkylene, alkenylene, cycloalkylene or cycloalkenylenegroup, or an aromatic hydrocarbon group one or more of carbon atoms ofwhich may be substituted by nitrogen atoms, such as a phenylene,pyridylene, benzylene, toluylene, xylylene, alkylphenylene,phenylenealkylene, biphenylene or phenylpyridylene group, with one ormore hydrogen atoms on the aromatic ring being optionally substituted byhydrocarbon groups. In each of these groups, one or more hydrogen atomsmay be substituted by halogen atoms such as fluorine, chlorine orbromine atoms to chemically feasible extent. X represents a group havinganionic property, such as a carboxylate, sulfonate or phosphate group.The carbon number of R⁷ may preferably range from 1 to 18. Preferably, kcan range from 1 to 18, m can range from 1 to 36, and n can be 0 or 1.

Structures of the above-described monomers (I-a to I-o) and blockcopolymers (II-a to II-e) composed of the monomers will be exemplifiedbelow, although the structures of block copolymers usable in the presentinvention are not limited to them.

The preferred numbers of the respective recurring units in the blockcopolymers (i.e., m, n and 1 in the above-exemplified recurring units(II-a) to (II-e)) may each independently range from 1 to 10,000. Morepreferably, their total (i.e., m+n+1 in the above-exemplified recurringunits (II-a) to (II-e)) may range from 10 to 20,000. The number averagemolecular weight may range preferably from 500 to 20,000,000, morepreferably from 1,000 to 5,000,000, most preferably from 2,000 to2,000,000. Usable as blocks formed of these polyvinyl ethers can includethose obtained by grafting the polyvinyl ethers on other polymers andthose obtained by copolymerizing the above-described vinyl monomers withother recurring unit structures.

No particular limitation is imposed on the process for the synthesis ofblock copolymers having recurring units formed of the above-describedvinyl ether monomers, respectively. Nonetheless, use of cation livingpolymerization makes it possible to synthesize various polymershomopolymers, copolymers formed of two or more monomers, blockcopolymers, graft polymers and graduation polymers, with their lengths(molecular weights) being precisely controlled. Further, variousfunctional groups can also be introduced on side chains of these blockcopolymers.

The water-based ink according to the present invention contains aluminum(including aluminum ions) or an aluminum compound in addition to theabove-described resin (block copolymer). This aluminum or aluminumcompound is concerned with the fixing property of the ink upon formingan image. The molar ratio of the resin (A) to the aluminum or aluminumcompound (B), A:B, in the ink may, therefore, be preferably from 1:5 to10,000:3, more preferably from 100:6 to 1,000:3.

If the molar ratio of the aluminum (aluminum compound) to the resin isunduly small, the ink according to the present invention may not beprovided with sufficient fixing property to a recording material and maybe unable to form an image with sufficient abrasion resistance,waterproofness and marker resistance. If the molar ratio of the aluminum(aluminum compound) to the resin is excessively large, on the otherhand, the water-based ink may be provided with lowered ejectionstability. As the aluminum compound, an aluminum-containing, organic orinorganic compound can be used.

Illustrative are alumina, aluminum hydroxide, tripropylaluminum,triisopropylaluminum, and aluminum compounds as Ziegler-Natta catalysts.

The improved ink fixing property, image waterproofness and imageabrasion resistance, which are available when an image is formed withthe ink of the present invention containing the resin and aluminum orthe aluminum compound, are considered to be attributable toagglomeration of the resin induced as a result of action of the aluminumcompound having cationic character or its ions on ether bond portions inthe resin.

When an organoaluminum compound is used as a catalyst in the productionof the above-described vinyl ether block copolymer, the content of theorganoaluminum compound in the resulting block copolymer may exceed theabove-described range. In such a case, it is preferred to purify thepolymer such that the content of the organoaluminum compound is loweredto bring the ratio of the resin to the organoaluminum compound to theabove-described molar ratio. The purification method of the polymer caninclude, but not limited to, washing with an acidic aqueous solution,dialysis, ultrafiltration, reprecipitation, and adsorption by anadsorbent. If the amount of aluminum (or aluminum compound) which wouldremain in the resulting block copolymer is known in the production ofthe block copolymer, the amounts of the resin and aluminum (or aluminumcompound) to be used, including the remaining aluminum (or aluminumcompound), can be set at the above-described molar ratio.

Examples of the colorant for use in the present invention include aciddyes, direct dyes, basic dyes, reactive dyes, food dyes, vat dyes,soluble vat dyes, reactive disperse dyes, disperse dyes, inorganicpigments, and organic pigments. Taking into consideration thewaterproofness of images to be formed, oil soluble dyes are morepreferred. Examples of dyes and pigments will be described belowalthough the present invention is not limited to them.

(Direct Dyes)

C.I. Direct Black 17, C.I. Direct Black 19, C.I. Direct Black 22, C.I.Direct Black 32, C.I. Direct Black 38, C.I. Direct Black 51, C.I. DirectBlack 62, C.I. Direct Black 71, C.I. Direct Black 108, C.I. Direct Black146, C.I. Direct Black 154; C.I. Direct Yellow 12, C.I. Direct Yellow24, C.I. Direct Yellow 26, C.I. Direct Yellow 44, C.I. Direct Yellow 86,C.I. Direct Yellow 87, C.I. Direct Yellow 98, C.I. Direct Yellow100,C.I. Direct Yellow 130, C.I. Direct Yellow 142;C.I. Direct Red 1,C.I. Direct Red 4, C.I. Direct Red 13, C.I. Direct Red 17, C.I. DirectRed 23, C.I. Direct Red 28, C.I. Direct Red 31, C.I. Direct Red 62, C.I.Direct Red 79, C.I. Direct Red 81, C.I. Direct Red 83, C.I. Direct Red89, C.I. Direct Red 227, C.I. Direct Red 240, C.I. Direct Red 242, C.I.Direct Red 243; C.I. Direct Blue 6, C.I. Direct Blue 22, C.I. DirectBlue 25, C.I. Direct Blue 71, C.I. Direct Blue 78, C.I. Direct Blue 86,C.I. Direct Blue 90, C.I. Direct Blue 106, C.I. Direct Blue 199; C.I.Direct Orange 34, C.I. Direct Orange 39, C.I. Direct Orange 44, C.I.Direct Orange 46, C.I. Direct Orange 60; C.I. Direct Violet 47, C.I.Direct Violet 48; C.I. Direct Brown 109; C.I. Direct Green 59; etc.;

(Acid Dyes)

C.I. Acid Black 2, C.I. Acid Black 7, C.I. Acid Black 24, C.I. AcidBlack 26, C.I. Acid Black 31, C.I. Acid Black 52, C.I. Acid Black 63,C.I. Acid Black 112, C.I. Acid Black 118, C.I. Acid Black 168, C.I. AcidBlack 172, C.I. Acid Black 208; C.I. Acid Yellow 11, C.I. Acid Yellow17, C.I. Acid Yellow 23, C.I. Acid Yellow 25, C.I. Acid Yellow 29, C.I.Acid Yellow 42, C.I. Acid Yellow 49, C.I. Acid Yellow 61, C.I. AcidYellow 71; C.I. Acid Red 1, C.I. Acid Red 6, C.I. Acid Red 8, C.I. AcidRed 32, C.I. Acid Red 37, C.I. Acid Red 51, C.I. Acid Red 52, C.I. AcidRed 80, C.I. Acid Red 85, C.I. Acid Red 87, C.I. Acid Red 92, C.I. AcidRed 94, C.I. Acid Red 115, C.I. Acid Red 180, C.I. Acid Red 254, C.I.Acid Red 256, C.I. Acid Red 289, C.I. Acid Red 315, C.I. Acid Red 317;C.I. Acid Blue 9, C.I. Acid Blue 22, C.I. Acid Blue 40, C.I. Acid Blue59, C.I. Acid Blue 93, C.I. Acid Blue 102, C.I. Acid Blue 104, C.I. AcidBlue 113, C.I. Acid Blue 117, C.I. Acid Blue 120, C.I. Acid Blue 167,C.I. Acid Blue 229, C.I. Acid Blue 234, C.I. Acid Blue 254; C.I. AcidOrange 7, C.I. Acid Orange 19; C.I. Acid Violet 49; etc.;

(Reactive Dyes)

C.I. Reactive Black 1, C.I. Reactive Black 5, C.I. Reactive Black 8,C.I. Reactive Black 13, C.I. Reactive Black 14, C.I. Reactive Black 23,C.I. Reactive Black 31, C.I. Reactive Black 34, C.I. Reactive Black 39;C.I. Reactive Yellow 2, C.I. Reactive Yellow 3, C.I. Reactive Yellow 13,C.I. Reactive Yellow 15, C.I. Reactive Yellow 17, C.I. Reactive Yellow18, C.I. Reactive Yellow 23, C.I. Reactive Yellow 24, C.I. ReactiveYellow 37, C.I. Reactive Yellow 42, C.I. Reactive Yellow 57, C.I.Reactive Yellow 58, C.I. Reactive Yellow 64, C.I. Reactive Yellow 75,C.I. Reactive Yellow 76, C.I. Reactive Yellow 77, C.I. Reactive Yellow79, C.I. Reactive Yellow 81, C.I. Reactive Yellow 84, C.I. ReactiveYellow 85, C.I. Reactive Yellow 87, C.I. Reactive Yellow 88, C.I.Reactive Yellow 91, C.I. Reactive Yellow 92, C.I. Reactive Yellow 93,C.I. Reactive Yellow 95, C.I. Reactive Yellow 102, C.I. Reactive Yellow111, C.I. Reactive Yellow 115, C.I. Reactive Yellow 116, C.I. ReactiveYellow 130, C.I. Reactive Yellow 131, C.I. Reactive Yellow 132, C.I.Reactive Yellow 133, C.I. Reactive Yellow 135, C.I. Reactive Yellow 137,C.I. Reactive Yellow 139, C.I. Reactive Yellow 140, C.I. Reactive Yellow142, C.I. Reactive Yellow 143, C.I. Reactive Yellow 144, C.I. ReactiveYellow 145, C.I. Reactive Yellow 146, C.I. Reactive Yellow 147, C.I.Reactive Yellow 148, C.I. Reactive Yellow 151, C.I. Reactive Yellow 162,C.I. Reactive Yellow 163; C.I. Reactive Red 3, C.I. Reactive Red 13,C.I. Reactive Red 16, C.I. Reactive Red 21, C.I. Reactive Red 22, C.I.Reactive Red 23, C.I. Reactive Red 24, C.I. Reactive Red 29, C.I.Reactive Red 31, C.I. Reactive Red 33, C.I. Reactive Red 35, C.I.Reactive Red 45, C.I. Reactive Red 49, C.I. Reactive Red 55, C.I.Reactive Red 63, C.I. Reactive Red 85, C.I. Reactive Red 106, C.I.Reactive Red 109, C.I. Reactive Red 111, C.I. Reactive Red 112, C.I.Reactive Red 113, C.I. Reactive Red 114, C.I. Reactive Red 118, C.I.Reactive Red 126, C.I. Reactive Red 128, C.I. Reactive Red 130, C.I.Reactive Red 131, C.I. Reactive Red 141, C.I. Reactive Red 151, C.I.Reactive Red 170, C.I. Reactive Red 171, C.I. Reactive Red 174, C.I.Reactive Red 176, C.I. Reactive Red 177, C.I. Reactive Red 183, C.I.Reactive Red 184, C.I. Reactive Red 186, C.I. Reactive Red 187, C.I.Reactive Red 188, C.I. Reactive Red 190, C.I. Reactive Red 193, C.I.Reactive Red 194, C.I. Reactive Red 195, C.I. Reactive Red 196, C.I.Reactive Red 200, C.I. Reactive Red 201, C.I. Reactive Red 202, C.I.Reactive Red 204, C.I., Reactive Red 206, C.I. Reactive Red 218, C.I.Reactive Red 221; C.I. Reactive Blue 2, C.I. Reactive Blue 3, C.I.Reactive Blue 5, C.I. Reactive Blue 8, C.I. Reactive Blue 10, C.I.Reactive Blue 13, C.I. Reactive Blue 14, C.I. Reactive Blue 15, C.I.Reactive Blue 18, C.I. Reactive Blue 19, C.I. Reactive Blue 21, C.I.Reactive Blue 25, C.I. Reactive Blue 27, C.I. Reactive Blue 28, C.I.Reactive Blue 38, C.I. Reactive Blue 39, C.I. Reactive Blue 40, C.I.Reactive Blue 41, C.I. Reactive Blue 49, C.I. Reactive Blue 52, C.I.Reactive Blue 63, C.I. Reactive Blue 71, C.I. Reactive Blue 72, C.I.Reactive Blue 74, C.I. Reactive Blue 75, C.I. Reactive Blue 77, C.I.Reactive Blue 78, C.I. Reactive Blue 79, C.I. Reactive Blue 89, C.I.Reactive Blue 100, C.I. Reactive Blue 101, C.I. Reactive Blue 104, C.I.Reactive Blue 104, C.I. Reactive Blue 105, C.I. Reactive Blue 119, C.I.Reactive Blue 122, C.I. Reactive Blue 147, C.I. Reactive Blue 158, C.I.Reactive Blue 160, C.I. Reactive Blue 162, C.I. Reactive Blue 166, C.I.Reactive Blue 169, C.I. Reactive Blue 170, C.I. Reactive Blue 171, C.I.Reactive Blue 172, C.I. Reactive Blue 173, C.I. Reactive Blue 174, C.I.Reactive Blue 176, C.I. Reactive Blue 179, C.I. Reactive Blue 184, C.I.Reactive Blue 190, C.I. Reactive Blue 191, C.I. Reactive Blue 194, C.I.Reactive Blue 195, C.I. Reactive Blue 198, C.I. Reactive Blue 204, C.I.Reactive Blue 211, C.I. Reactive Blue 216, C.I. Reactive Blue 217; C.I.Reactive Orange 5, C.I. Reactive Orange 7, C.I. Reactive Orange 11, C.I.Reactive Orange 12, C.I. Reactive Orange 13, C.I. Reactive Orange 15,C.I. Reactive Orange 16, C.I. Reactive Orange 35, C.I. Reactive Orange45, C.I. Reactive Orange 46, C.I. Reactive Orange 56, C.I. ReactiveOrange 62, C.I. Reactive Orange 70, C.I. Reactive Orange 72, C.I.Reactive Orange 74, C.I. Reactive Orange 82, C.I. Reactive Orange 84,C.I. Reactive Orange 87, C.I. Reactive Orange 91, C.I. Reactive Orange92, C.I. Reactive Orange 93, C.I. Reactive Orange 95, C.I. ReactiveOrange 97, C.I. Reactive Orange 99; C.I. Reactive Violet 1, C.I.Reactive Violet 4, C.I. Reactive Violet 5, C.I. Reactive Violet 6, C.I.Reactive Violet 22, C.I. Reactive Violet 24, C.I. Reactive Violet 33,C.I. Reactive Violet 36, C.I. Reactive Violet 38; C.I. Reactive Green 5,C.I. Reactive Green 8, C.I. Reactive Green 12, C.I. Reactive Green 15,C.I. Reactive Green 19, C.I. Reactive Green 23; C.I. Reactive Brown 2,C.I. Reactive Brown 7, C.I. Reactive Brown 8, C.I. Reactive Brown 9,C.I. Reactive Brown 11, C.I. Reactive Brown 16, C.I. Reactive Brown 17,C.I. Reactive Brown 18, C.I. Reactive Brown 21, C.I. Reactive Brown 24,C.I. Reactive Brown 26, C.I. Reactive Brown 31, C.I. Reactive Brown 32,C.I. Reactive Brown 33; etc.;

(Basic Dyes)

C.I. Basic Black 2; C.I. Basic Red 1, C.I. Basic Red 2, C.I. Basic Red9, C.I. Basic Red 12, C.I. Basic Red 13, C.I. Basic Red 14, C.I. BasicRed 27; C.I. Basic Blue 1, C.I. Basic Blue 3, C.I. Basic Blue 5, C.I.Basic Blue 7, C.I. Basic Blue 9, C.I. Basic Blue 24, C.I. Basic Blue 25,C.I. Basic Blue 26, C.I. Basic Blue 28, C.I. Basic Blue 29; C.I. BasicViolet 7, C.I. Basic Violet 14, C.I. Basic Violet 27; C.I. Food Black 1,C.I. Food Black 2; etc.;

(Oil-Soluble Dyes)

C.I. Solvent Yellow 1, C.I. Solvent Yellow 2, C.I. Solvent Yellow 3,C.I. Solvent Yellow 13, C.I. Solvent Yellow 19, C.I. Solvent Yellow 22,C.I. Solvent Yellow 29, C.I. Solvent Yellow 36, C.I. Solvent Yellow 37,C.I. Solvent Yellow 38, C.I. Solvent Yellow 39, C.I. Solvent Yellow 40,C.I. Solvent Yellow 43, C.I. Solvent Yellow 44, C.I. Solvent Yellow 45,C.I. Solvent Yellow 47, C.I. Solvent Yellow 62, C.I. Solvent Yellow 63,C.I. Solvent Yellow 71, C.I. Solvent Yellow 76, C.I. Solvent Yellow 81,C.I. Solvent Yellow 85, C.I. Solvent Yellow 86, etc.; C.I. Solvent Red35, C.I. Solvent Red 36, C.I. Solvent Red 37, C.I. Solvent Red 38, C.I.Solvent Red 39, C.I. Solvent Red 40, C.I. Solvent Red 58, C.I. SolventRed 60, C.I. Solvent Red 65, C.I. Solvent Red 69, C.I. Solvent Red 81,C.I. Solvent Red 86, C.I. Solvent Red 89, C.I. Solvent Red 92, C.I.Solvent Red 97, C.I. Solvent Red 99, C.I. Solvent Red 100, C.I. SolventRed 109, C.I. Solvent Red 118, C.I. Solvent Red 119, C.I. Solvent Red122, etc.; C.I. Solvent Blue 14, C.I. Solvent Blue 24, C.I. Solvent Blue26, C.I. Solvent Blue 34, C.I. Solvent Blue 37, C.I. Solvent Blue 39,C.I. Solvent Blue 42, C.I. Solvent Blue 43, C.I. Solvent Blue 45, C.I.Solvent Blue 48, C.I. Solvent Blue 52, C.I. Solvent Blue 53, C.I.Solvent Blue 55, C.I. Solvent Blue 59, C.I. Solvent Blue 67, etc.; C.I.Solvent Black 5, C.I. Solvent Black 8, C.I. Solvent Black 14, C.I.Solvent Black 17, C.I. Solvent Black 19, C.I. Solvent Black 20, C.I.Solvent Black 22, C.I. Solvent Black 24, C.I. Solvent Black 26, C.I.Solvent Black 28, C.I. Solvent Black 43, etc.;

(Pigments)

“Raven 760 Ultra”, “Raven 1060 Ultra”, “Raven 1080”, “Raven 1100 Ultra”,“Raven 1170”, “Raven 1200”, “Raven 1250”, “Raven 1255”, “Raven 1500”,“Raven 2000”, “Raven 2500 Ultra”, “Raven 3500”, “Raven 5250”, “Raven5750”, “Raven 7000”, “Raven 5000 ULTRA-II”, “Raven 1190 ULTRA-II” (tradenames, products of Columbian Carbon Co.); “Black PearlsL”, “MOGULL”,“RegaL-330R”, “RegaL-400R”, “RegaL-660R”, “Monarch-800”, “Monarch-880”,“Monarch-900”, “Monarch-1000”, “Monarch-1300”, “Monarch-1400” (tradenames, products of Cabot Corporation);

-   -   “Color Black FW1”, “Color Black FW2”, “Color Black FW200”,        “Color Black 18”, “Color Black S160”, “Color Black S170”,        “Special Black 4”, “Special Black 4A”, “Special Black 6”,        “Special Black 550”, “Printex 35”, “Printex 45”, “Printex 55”,        “Printex 85”, “Printex 95”, “Printex U”, “Printex 140U,”,        “Printex V”, “Printex 140V” (trade names, products of Degussa        AG); “No. 25”, “No. 33”, “No. 40”, “No. 45”, “No. 47”, “No. 52”,        “No. 900”, “No. 970”, “No. 2200B”, “No. 2300”, “No. 2400B”,        “MCF-88”, “MA600”, “MA77”, “MA8”, “MA100”, “MA230”, “MA220”        (trade names; products of Mitsubishi Chemical Corporation);    -   C.I. Pigment Blue 1, C.I. Pigment Blue 2, C.I. Pigment Blue 3,        C.I. Pigment Blue 15, C.I. Pigment Blue 15:2, C.I. Pigment Blue        15:3, C.I. Pigment Blue 15:4, C.I. Pigment Blue 16, C.I. Pigment        Blue 22, C.I. Pigment Blue 60, etc.; C.I. Pigment Red 5, C.I.        Pigment Red 7, C.I. Pigment Red 12, C.I. Pigment Red 48, C.I.        Pigment Red 48:1, C.I. Pigment Red 57, C.I. Pigment Red 112,        C.I. Pigment Red 122, C.I. Pigment Red 123, C.I. Pigment Red        146, C.I. Pigment Red 168, C.I. Pigment Red 184, C.I. Pigment        Red 202, C.I. Pigment Red 207, etc.;    -   C.I. Pigment Yellow 12, C.I. Pigment Yellow 13, C.I. Pigment        Yellow 14, C.I. Pigment Yellow 16, C.I. Pigment Yellow 17, C.I.        Pigment Yellow 74, C.I. Pigment Yellow 83, C.I. Pigment Yellow        93, C.I. Pigment Yellow 95, C.I. Pigment Yellow 97, C.I. Pigment        Yellow 98, C.I. Pigment Yellow 114, C.I. Pigment Yellow 128,        C.I. Pigment Yellow 129, C.I. Pigment Yellow 151, C.I. Pigment        Yellow 154, etc.

The weight ratio of the colorant (A) to the ink (B), A:B, in the ink mayrange preferably from 1:0.01 to 1:2 in terms of solids. An excessivelysmall resin amount may result in an ink having insufficient fixingproperty to a recording material so that an image formed with the inkmay be insufficient in abrasion resistance, waterproofness, markerresistance and the like. An unduly large resin amount, on the otherhand, may result in a water-based ink having high viscosity so that thewater-based ink may be provided with reduced ejection stability andanti-clogging property.

The water-based ink according to the present invention requires anaqueous medium for dispersing or dissolving the colorant and resin. Theaqueous medium may contain an organic solvent which is at leastwater-soluble. Preferably, a mixed solvent of water and a water-solubleorganic solvent is used as an aqueous medium for the water-based ink. Inthe present invention, the preferred proportion of the water-solubleorganic solvent in the aqueous medium may be, for example, from 5 to 50wt. %, with a range of from 10 to 40 wt. % being more preferred.

The water-soluble organic solvent is used in the water-base ink of thepresent invention to prevent solidification of the ink in nozzleportions due to its drying. Examples of such water-soluble organicsolvents can include lower alcohols such as methyl alcohol, ethylalcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butylalcohol and tertbutyl alcohol; diols such as ethylene glycol,diethyleneglycol, triethyleneglycol, tetraethyleneglycol, propyleneglycol, butylene glycol, dipropylene glycol, tripropylene glycol,hexylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol,thiodiglycol and 1,4-cyclohexanediol; triols such as glycerin,1,2,4-butanetriol, 1,2,6-hexanetriol and 1,2,5-pentanetriol; hinderedalcohols such as trimethylolpropane, trimethylolethane, neopentylglycoland pentaerythritol; glycol ethers such as ethylene glycol monomethylether, ethylene glycol monoethyl ether, ethylene glycol monoisoproylether, ethylene glycol monoallyl ether, diethylene glycol monomethylether, diethylene glycol monoethyl ether, triethylene glycol monomethylether, triethylene glycol monoethyl ether, propylene glycol monomethylether and dipropylene glycol monomethyl ether; dimethylsulfoxide,glycerin monoallyl ether, polyethylene glycol, polypropylene glycol,N-methyl-2-pyrrolidone, 2-pyrrolidone, γ-butyrolactone,1,3-dimethyl-2-imidazolidinone, sulfolane, β-dihydroxyethylurea, urea,acetonylacetone, dimethylformamide, dimethylacetamide, acetone,diacetone alcohol, tetrahydrofuran, and dioxane.

Particularly preferred, water-soluble organic solvents are glycerin andpolyhydric alcohols other than glycerin, for example, diethylene glycol,ethylene glycol, polyethylene glycol, propylene glycol and the like. Twoor more of such water-soluble organic solvents may be used incombination in the water-based ink.

In a preferred embodiment of the present invention, the ink containswater together with the water-soluble organic solvent. The preferredproportion of water in the aqueous medium may be, for example, 50 wt. %or more but less than 100 wt. %, with a range of 60 wt. % or more butless than 100 wt. % being more preferred. Preferably usable can be purewater, membrane filter-treated water, distilled and/or ion-changeresin-treated water as water in the invention.

The preferred proportion of the colorant in the water-based inkaccording to the present invention may be, for example, from 0.1 to 20wt. % based on the whole weight of the water-based ink, with a range offrom 1 to 10 wt. % being more preferred. A colorant proportion smallerthan 1 wt. % may have difficulty in providing printed images withsufficient image density in some instances, while a colorant proportiongreater than 10 wt. % may lead to a reduction in ejection stability, forexample, due to clogging at nozzles without bringing about anysignificant improvement in image density.

The preferred proportion of the resin in the water-based ink accordingto the present invention may be, for example, from 0.001 to 40 wt. %based on the whole weight of the water-based ink, with a range of from0.01 to 20 wt. % being more preferred. A resin proportion smaller than0.001 wt. % may result in images reduced in abrasion resistance, markerresistance and the like, while a resin proportion greater than 40 wt. %may result in a water-based ink of higher viscosity, possibly leading toa reduction in ejection stability, for example, due to clogging atnozzles.

To the water-based ink according to the present invention, variousadditives other than the above-described components may be addedincluding, for example, surfactants, pH adjusters, antioxidants andantimolds. The preferred viscosity of the water-based ink according tothe present invention may range from 1.0 mPa·s to 5.0 mPa·s at 25° C.

The inkjet recording process according to the present invention ischaracterized in that an image is formed by an inkjet recording systemwhile using the water-based ink according to the present invention.Thermal energy or mechanical energy can be used as energy in inkjetrecording, although use of thermal energy is preferred. No particularlimitation is imposed on a recording material for use in the inkjetrecording process of the present invention. Nonetheless, a recordingmaterial provided on at least one side thereof with an ink-receivingcoating layer, which is commonly called “exclusive inkjet paper”, can beused preferably. Desired is, for example, a recording material providedon at least one side thereof with an ink-receiving coating layer whichcontains at least a hydrophilic polymer and/or an inorganic porousmaterial. The image formed by the inkjet recording process is excellentin ink fixing property and is good in abrasion resistance,waterproofness and marker resistance.

EXAMPLES

Based on Production Examples, Examples and Comparative Examples, thepresent invention will next be described more specifically. It is,however, to be noted that the present invention shall not be limited bythe following Examples unless it departs from the gist thereof. In thefollowing description, all designations of “part” or “parts” and “%” areon a weight basis unless otherwise specifically indicated. In each ofthe following Examples, the molecular weight and molecular weightdistribution of the resin were measured using GPC (Gel PermeationChromatograph) (“HLC8220GPC”, trade name; manufactured by TOSOHCORPORATION), identification of the resin was performed based on itsmeasurement by an NMR spectrometer (“DPX400”, trade name; manufacturedby Bruker BioSpin Corp.), and each concentration of aluminum is a valuemeasured by using an ICP optical emission spectrometer (inductivelycoupled plasma emission spectrometer) (“SPS 1700HV”, trade name;manufactured by Seiko Instruments Inc.)

Production Example 1

[Synthesis of an A-B-C Triblock Copolymer (Resin A)]

A glass vessel fitted with a three-way cock was purged with nitrogengas, and then, heated at 250° C. under a nitrogen gas atmosphere toremove any adsorbed water. After the system was allowed to cool down toroom temperature, 1-isobutoxyethyl vinyl ether (10 mmol), ethyl acetate(16 mmol), 1-isobutoxyethyl acetate (0.1 mmol) and toluene (11 cm³) werecharged. When the internal temperature of the system had dropped to 0°C., ethyl aluminum sesquichloride (0.2 mmol) was added to initiatepolymerization, and A segments of a triblock copolymer were synthesized.

Using the gel permeation column chromatograph (GPC), the molecularweight was monitored in a time division manner. Subsequent to thecompletion of the polymerization of the A segments, 2-methoxyethyl vinylether (12 mmol) was added to conduct synthesis of B segments. Aftercompletion of the polymerization of the B segments had been confirmed bymonitoring the polymerization with GPC in a similar manner as describedabove, ethyl 4-(2-vinyloxyethoxy)benzoate (12 mmol) was added to conductsynthesis of C segments. Termination of the polymerization reaction waseffected by adding into the system a 0.3% solution of ammonia inmethanol.

Identification of the resultant triblock copolymer was conducted usingNMR and GPC. It was possible to obtain satisfactory spectra in both ofthe analyses [number average molecular weight (estimated based on thestandard polystyrene calibration) Mn=3.7×10⁴, Mn/Mw=1.3 (Mw: weightaverage molecular weight (estimated based on the standard polystyrenecalibration))].

To adjust the content of aluminum in the thus-obtained resin, samples ofthe resin were washed with a 0.6 N aqueous solution of hydrochloric acidto conduct purification of the resin such that the molar ratios of theresin to the aluminum in the individual samples reached the valuesdescribed in Table 1 to obtain aluminum-containing resins havingdifferent aluminum contents. The molar numbers of aluminum are Valuesdetermined from the concentrations of aluminum in the individual resinsamples. Ester portions in the C segments in the triblock copolymer werehydrolyzed in a mixed solvent of sodium hydroxide (5-fold equivalents)and methanol to convert the C segments into carboxylic acid polymers.

Examples 1-4 and Comparative Examples 1-4

The water-based inks of the Examples and the Comparative Examples wereprepared by mixing the resin A, which had been purified as describedabove and contained aluminum at the corresponding content, with thecorresponding colorant at the ratio shown in Table 1, adding diethyleneglycol (20%) and “Acetylenol EH” (trade name for a surfactant producedby Kawaken Fine Chemicals Co., Ltd.; 0.15%), stirring the resultantmixture for 10 minutes, adding water in such an amount that the solidcontent of the colorant would finally reach 5% in the water-based ink,and then stirring the thus-obtained mixture. Further, each of thewater-based inks so obtained was subjected to filtration under reducedpressure through a 0.2 μm membrane filter (product of Toyo Roshi Kaisha,Ltd.). TABLE 1 Colorant/resin (concentration Resin/Al Colorant in ink)(molar ratio) Example 1 C.I. Solvent 5%/5%   100/6 Yellow 1 Example 2C.I. Direct Black 17 Example 3 C.I. Solvent  1,000/3 Yellow 1 Example 4C.I. Direct Black 17 Comp. Ex. 1 C.I. Solvent 10,000/1 Yellow 1 Comp.Ex. 2 C.I. Direct Black 17 Comp. Ex. 3 C.I. Solvent     1/10 Yellow 1Comp. Ex. 4 C.I. Direct Black 17

Using the above-described inks of the Examples and Comparative Examples,recording was conducted on commercial copying paper (plain paper), “HKGenshi (Base Paper)” (product of Daishowa Paper Manufacturing Co.,Ltd.), and glossy paper, “SP101” (product of Canon Inc.). Formation ofan image (printing) was conducted using a water-based inkjet printer,“F660” (manufactured by Canon Inc.). Ranking of the prints was performedas will be described below. The ranking results are presented in Table2. With the water-based inks of Examples 1-4, good results were obtainedon both of the plain paper and the glossy paper as presented in Table 2.

(Abrasion Resistance)

After a printed paper had been left over for 12 hours or longersubsequent to its printing, “KIM WIPE” (trade name; product of CRECIACorporation) was placed on the printed paper. Further, a weight of 500g/12.56 cm² was placed on the “KIM WIPE”. The weight was then caused toslide 5 strokes. With the naked eye, a blank area was observed for asmear, and a solid printed image and a character printed area wereobserved for rubbing. Ranking was performed in accordance with thefollowing ranking standards. The ranking results are presented in Table2.

-   -   A: A blank area is free of any smear, and a solid-printed image        and a character-printed area are also free of rubbing.    -   B: A blank area has a slight smear, and a solid-printed image        and a character-printed area contain traces of slight rubbing.    -   C: A blank area has a smear, and a solid-printed image and a        character-printed area have been rubbed off at some parts        thereof.        (Waterproofness)

After a printed paper had been left over for 12 hours or longersubsequent to its printing, the reflection density of the image wasmeasured. Further, the printed paper was kept still for 5 minutes in tapwater. After water was dried off, the reflection density of the imagewas measured to determine, as a scale of waterproofness, a percentremainder of the reflection density after a waterproofness test.

Ranking was performed in accordance with the following rankingstandards. The ranking results are presented below in Table 2.

-   -   A: Percent remainder of image density≧90%    -   B: 90%>Percent remainder of image density≧80%    -   C: 80%>Percent remainder of image density≧70%        (Marker Resistance)

After a printed paper had been left over for 12 hours or longersubsequent to printing characters thereon, the character-printed areawas marked once under an ordinary writing pressure with a yellow markerpen manufactured by ZEBRA PEN CORPORATION. Its marker resistance wasranked in accordance with the following ranking standards. The rankingresults are presented below in Table 2.

-   -   A: Neither bleeding at a printed area nor a smear at a blank        area is observed, and a felt tip is not smeared either.    -   B: A blank area has a slight smear, while a printed area has        slight bleeding.    -   C: A blank area has a smear, while a printed area has bleeding.        (Jettability)

The conditions of each printed image and the heater surface of an inkhead after its printing were observed. Ranking was performed inaccordance with the following ranking standards.

-   -   A: A solid-printed image area and a character-printed area are        both successfully printed neat, and practically no deposit is        observed on the heater surface.    -   B: A solid-printed image area and a character-printed area are        both successfully printed neat, but a small deposit is observed        on a heater surface.

C: A solid-printed image area and a character-printed area are bothblurred, and a large deposit is observed on a heater surface. TABLE 2Abrasion resistance Waterproofness Marker resistance Plain Glossy PlainGlossy Plain Glossy paper paper paper paper paper paper Jettability Ex.1 A A A A A A A Ex. 2 A A A A A A A Ex. 3 A A A A A A A Ex. 4 A A A A AA A Comp. A A A A B B A Ex. 1 Comp. A A B A B B A Ex. 2 Comp. — — — — —— C* Ex. 3 Comp. — — — — — — C* Ex. 4*The inks of Comparative Examples 3 and 4 were so poor in jettabilitythat the ranking of abrasion resistance, waterproofness and markerresistance was not feasible.

Production Example 2

[Synthesis of an A-B-C Triblock Copolymer (Resin B)]

A glass vessel fitted with a three-way cock was purged with nitrogengas, and then, heated at 250° C. under a nitrogen gas atmosphere toremove any adsorbed water. After the system was allowed to cool down toroom temperature, isobutoxyl vinyl ether (12 mmol) as a hydrophobicmonomer, ethyl acetate (16 mmol) and toluene (11 mL) were charged. Whenthe internal temperature of the system had dropped to 0° C., ethylaluminum sesquichloride (0.2 mmol) was added to initiate polymerization,and A segments of a triblock copolymer were synthesized.

Using GPC, the molecular weight was monitored in a time division manner.Subsequent to the completion of the polymerization of the A segments,2-methoxyethyl vinyl ether (12 mmol) was added as a hydrophilic monomerto conduct synthesis of B segments.

After completion of the polymerization of the B segments had beenconfirmed by monitoring the polymerization with GPC in a similar manneras described above, ethyl 4-(2-vinyloxyethoxy)benzoate (12 mmol), wasadded as a hydrophilic monomer to conduct synthesis of C segments.Termination of the polymerization reaction was effected by adding intothe system a 0.3% solution of ammonia in methanol.

Identification of the resultant triblock copolymer was conducted usingNMR and GPC. It was possible to obtain satisfactory spectra in both ofthe analyses [number average molecular weight (estimated based on thestandard polystyrene calibration) Mn=3.7×10⁴, Mn/Mw=1.3 (Mw: weightaverage molecular weight (estimated based on the standard polystyrenecalibration))].

To adjust the content of aluminum in the thus-obtained resin, samples ofthe resin were washed with a 0.6 N aqueous solution of hydrochloric acidto conduct purification of the resin such that the molar ratios of theresin to the aluminum in the individual samples reached the valuesdescribed in Table 3 to obtain aluminum-containing resins havingdifferent aluminum contents. The molar numbers of aluminum are valuesdetermined from the concentrations of aluminum in the individual resinsamples. Ester portions in the C segments in the triblock copolymer werehydrolyzed in a mixed solvent of sodium hydroxide (5-fold equivalents)and methanol, and the solvent was distilled off to obtain a carboxylicacid polymer.

Examples 5-8 and Comparative Examples 5-8

Water-based inks were prepared in a similar manner as in Examples 1-4and Comparative Examples 1-4 except that the formulas in Table 3 werefollowed and the resin was changed from the resin A to the resin B.Printing and ranking of prints were also performed likewise. The rankingresults are presented in Table 4. TABLE 3 Colorant/resin (concentrationResin/Al Colorant in ink) (molar ratio) Example 5 C.I. Solvent 5%/5%  100/6 Yellow 1 Example 6 C.I. Direct Black 17 Example 7 C.I. Solvent 1,000/3 Yellow 1 Example 8 C.I. Direct Black 17 Comp. Ex. 5 C.I.Solvent 10,000/1 Yellow 1 Comp. Ex. 6 C.I. Direct Black 17 Comp. Ex. 7C.I. Solvent     1/10 Yellow 1 Comp. Ex. 8 C.I. Direct Black 17

TABLE 4 Abrasion resistance Waterproofness Marker resistance PlainGlossy Plain Glossy Plain Glossy paper paper paper paper paper paperJettability Ex. 5 A A A A A A A Ex. 6 A A A A A A A Ex. 7 A A A A A A AEx. 8 A A A A A A A Comp. A A A A B B A Ex. 5 Comp. A A B A B B A Ex. 6Comp. — — — — — — C* Ex. 7 Comp. — — — — — — C* Ex. 8*The inks of Comparative Examples 7 and 8 were so poor in jettabilitythat the ranking of abrasion resistance, waterproofness and markerresistance was not feasible.

Production Example 3

[Synthesis of an A-B Diblock Copolymer (Resin C)]

A glass vessel fitted with a three-way cock was purged with nitrogengas, and then, heated at 250° C. under a nitrogen gas atmosphere toremove any adsorbed water. After the system was allowed to cool down toroom temperature, 2-decanoxyethyl vinyl ether (12 mmol), ethyl acetate(16 mmol), 1 isobutoxyethyl acetate (0.1 mmol) and toluene (11 cm³) werecharged. When the internal temperature of the system had dropped to 0°C., ethyl aluminum sesquichloride (0.2 mmol) was added to initiatepolymerization, and the A blocks of an A-B diblock copolymer weresynthesized.

Using a gel permeation chromatography (GPC), the molecular weight wasmonitored in a time division manner. Subsequent to the completion of thepolymerization of the A blocks, ethyl 4-(2-vinyloxyethoxy)benzoate (12mmol) was added to conduct synthesis of B blocks. Termination of thepolymerization reaction was effected by adding into the system a 0.3%solution of ammonia in methanol.

Identification of the resultant diblock copolymer was conducted usingNMR and GPC. It was possible to obtain satisfactory spectra in both ofthe analyses [number average molecular weight (estimated based on thestandard polystyrene calibration) Mn=3.5×10⁴, Mn/Mw=1.2 (Mw: weightaverage molecular weight (estimated based on the standard polystyrenecalibration))].

To adjust the content of aluminum in the thus-obtained resin, samples ofthe resin were washed with a 0.6 N aqueous solution of hydrochloric acidto conduct purification of the resin such that the molar ratios of theresin to the aluminum in the individual samples reached the valuesdescribed in Table 5 to obtain aluminum-containing resins havingdifferent aluminum contents. The molar numbers of aluminum are valuesdetermined from the concentrations of aluminum in the individual resinsamples. Ester portions in B segments in the diblock copolymer werehydrolyzed in a mixed solvent of sodium hydroxide (5-fold equivalents)and methanol, and the solvent was distilled off to obtain a carboxylicacid polymer.

Examples 9-12 and Comparative Examples 9-12

Water-based inks were prepared in a similar manner as in Examples 1-4and Comparative Examples 1-4 except that the formulas in Table 5 werefollowed and the resin was changed from the resin A to the resin C.Printing and ranking of prints were also performed likewise. The rankingresults are presented in Table 6. TABLE 5 Colorant/resin (concentrationResin/Al Colorant in ink) (molar ratio) Example 9 C.I. Solvent 5%/5%  100/6 Yellow 1 Example 10 C.I. Direct Black 17 Example 11 C.I. Solvent 1,000/3 Yellow 1 Example 12 C.I. Direct Black 17 Comp. Ex. 9 C.I.Solvent 10,000/1 Yellow 1 Comp. Ex. 10 C.I. Direct Black 17 Comp. Ex. 11C.I. Solvent     1/10 Yellow 1 Comp. Ex. 12 C.I. Direct Black 17

TABLE 6 Abrasion resistance Waterproofness Marker resistance PlainGlossy Plain Glossy Plain Glossy paper paper paper paper paper paperJettability Ex. 9 A A A A A A A Ex. 10 A A A A A A A Ex. 11 A A A A A AA Ex. 12 A A A A A A A Comp. A A A A B B A Ex. 9 Comp. A A B A B B A Ex.10 Comp. — — — — — — C* Ex. 11 Comp. — — — — — — C* Ex. 12*The inks of Comparative Examples 11 and 12 were so poor in jettabilitythat the ranking of abrasion resistance, waterproofness and markerresistance was not feasible.

Production Example 4

[Synthesis of an A-B Diblock Copolymer (Resin D)]

A glass vessel fitted with a three-way cock was purged with nitrogengas, and then, heated at 250° C. under a nitrogen gas atmosphere toremove any adsorbed water. After the system was allowed to cool down toroom temperature, isobutyl vinyl ether (12 mmol), ethyl acetate (16mmol), 1 isobutoxyethyl acetate (0.1 mmol) and toluene (11 cm³) werecharged. When the internal temperature of the system had dropped to 0°C., ethyl aluminum sesquichloride ((0.2 mmol) was added to initiatepolymerization, and the A blocks of an A-B diblock copolymer wassynthesized.

Using a gel permeation column chromatography (GPC), the molecular weightwas monitored in a time division manner. Subsequent to the completion ofthe polymerization of the A blocks, a vinyl monomer (12 mmol) which hadbeen obtained by silylating the hydroxyl group of 2-hydroxyethyl vinylether with trimethylchlorosilane was added to conduct synthesis of Bblocks. Termination of the polymerization reaction was effected byadding into the system a 0.3% solution of ammonia in methanol.

Identification of the resultant diblock copolymer was conducted usingNMR and GPC. It was possible to obtain satisfactory spectra in both ofthe analyses [number average molecular weight (estimated based on thestandard polystyrene calibration) Mn=3.7×10⁴, Mn/Mw=1.3 (Mw: weightaverage molecular weight (estimated based on the standard polystyrenecalibration))].

To adjust the content of aluminum in the thus-obtained resin, samples ofthe resin were washed with a 0.6 N aqueous solution of hydrochloric acidto conduct purification of the resin such that the molar ratios of theresin to the aluminum in the individual samples reached the valuesdescribed in Table 7 to obtain aluminum-containing resins havingdifferent aluminum contents. The molar numbers of aluminum are valuesdetermined from the concentrations of aluminum in the individual resinsamples. Hydrolysis of the hydroxyl group silylated withtrimethylchlorosilane was conducted by adding water.

Examples 13-16 and Comparative Examples 13-16

Water-based inks were prepared in a similar manner as in Examples 1-4and Comparative Examples 1-4 except that the formulas in Table 7 werefollowed and the resin was changed from the resin A to the resin D.Printing and ranking of prints were also performed likewise. The rankingresults are presented in Table 8. TABLE 7 Colorant/resin (concentrationResin/Al Colorant in ink) (molar ratio) Example 13 C.I. Solvent 5%/5%  100/6 Yellow 1 Example 14 C.I. Direct Black 17 Example 15 C.I. Solvent 1,000/3 Yellow 1 Example 16 C.I. Direct Black 17 Comp. Ex. 13 C.I.Solvent 10,000/1 Yellow 1 Comp. Ex. 14 C.I. Direct Black 17 Comp. Ex. 15C.I. Solvent     1/10 Yellow 1 Comp. Ex. 16 C.I. Direct Black 17

TABLE 8 Abrasion resistance Waterproofness Marker resistance PlainGlossy Plain Glossy Plain Glossy paper paper paper paper paper paperJettability Ex. 13 A A A A A A A Ex. 14 A A A A A A A Ex. 15 A A A A A AA Ex. 16 A A A A A A A Comp. A A A A B B A Ex. 13 Comp. A A B A B B AEx. 14 Comp. — — — — — — C* Ex. 15 Comp. — — — — — — C* Ex. 16*The inks of Comparative Examples 15 and 16 were so poor in jettabilitythat the ranking of abrasion resistance, waterproofness and markerresistance was not feasible.

INDUSTRIAL APPLICABILITY

As has been described in the above, the present invention can providewater-based inks excellent in abrasion resistance, waterproofness andmarker resistance and also good in the stability of ejection at nozzles.

1. A water-based inkjet printer ink comprising at least a colorant and aresin, wherein said resin is a block copolymer comprising at least onehydrophilic block and at least one hydrophobic block, each of saidblocks is a vinyl ether polymer, and said ink further comprises aluminumor an aluminum compound.
 2. A water-based inkjet printer ink accordingto claim 1, wherein a molar ratio of said resin to said aluminum oraluminum compound is from 1:5 to 10,000:3.
 3. A water-based inkjetprinter ink according to claim 1, wherein a molar ratio of said resin tosaid aluminum or aluminum compound is from 100:6 to 1,000:3.
 4. Awater-based inkjet printer ink according to claim 1, wherein said blockcopolymer has a number average molecular weight of from 500 to20,000,000.
 5. A water-based inkjet printer ink according to claim 1,wherein said aluminum compound is at least one aluminum compoundselected from the group consisting of alumina, aluminum hydroxide,tripropylaluminum, triisopropylaluminum, and aluminum compounds asZiegler-Natta catalysts.
 6. A water-based inkjet printer ink accordingto claim 1, wherein said colorant is an oil-soluble dye.
 7. An inkjetrecording process wherein an image is formed by an inkjet recordingsystem while using an water-based inkjet printer ink according to anclaim 1.